Cow’s Milk Protein Allergy – What is it?

Understanding Cow’s Milk Protein Allergy (CMPA)
Written by Registered Dietitian Nishti

Cow’s milk protein allergy (CMPA) is the most common food allergy in babies and young children. It can cause a wide range of symptoms — some appear quickly (IgE-mediated) and others appear more slowly (non-IgE mediated).

CMPA can affect formula-fed, breastfed, or mixed-fed babies. This is because small amounts of dairy from the mother’s diet can pass into breast milk.

🌱 What Causes CMPA?

Some babies are more likely to develop CMPA if there’s a family history of:

• Eczema

• Asthma or hay fever

• Other food allergies

Other factors that may increase the risk include:

• Antibiotic use

• Medicines like omeprazole

• C-section birth

• Low vitamin D levels

⚠️ CMPA Symptoms – What to Look For

Symptoms can vary widely. Some babies may have just one symptom, like constipation. Others may show several signs, such as reflux, eczema, or colic.

Delayed Symptoms (Non-IgE Mediated)

These appear slowly over time.

Gut symptoms:

• Reflux

• Loose or bloody/mucus-filled stools

• Tummy pain or colic

• Constipation

• Food refusal

• Slow weight gain

• Redness around the bottom

Skin and respiratory:

• Itchy skin or rash

• Eczema

• Mucus in the nose/throat

Immediate Symptoms (IgE Mediated)

These come on quickly, often within minutes.

Gut:

• Swollen lips or mouth

• Itching in the mouth

• Vomiting, diarrhoea

• Colicky pain

Skin:

• Hives or itchy rash

• Swelling around lips, eyes or face

Respiratory:

• Coughing, sneezing, wheezing

• Nasal itching or congestion

Other common symptoms seen in practice:

• Repeated ear infections

• Disturbed sleep

❌ CMPA is Not Lactose Intolerance

Lactose intolerance is not an allergy. It happens when the body doesn't make enough of the enzyme lactase.

CMPA is an immune response to milk protein, not milk sugar.

Children can develop temporary lactose intolerance after a tummy bug, but this usually improves within a few weeks on a lactose-free diet.

🩺 How is CMPA Diagnosed?

For delayed (non-IgE) CMPA:

• Your dietitian or doctor will take a detailed history

• You’ll trial removing dairy for 2–4 weeks

• Then reintroduce it to see if symptoms return

For immediate (IgE) CMPA:

• A skin prick or blood test may be done

🌈 Will My Child Outgrow CMPA?

Yes — most children outgrow it, usually by age 3.

Compared to peanut allergy, which only 1 in 10 children outgrow, milk allergy has a much higher recovery rate (up to 85%).

How quickly your child outgrows it depends on both the food and how severe their allergy is.

💬 If you think your baby might have CMPA, you’re not alone. Help is available — and things do get better.